Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.1998.363.365JavedMuhammad SheriA. N. 4199814The impact of three iso-caloric test diets, viz. 30, 35 and 40 percent crude protein (C.P.) on the physico-chemical characteristics of water and grass carp yields was studied for 270 days. In control treatment, fish yield was 84.47 percent dependent on water nitrates, phosphates and temperature while nitrates along with hardness, alkalinity, pH and temperature accounted for 85.90 percent variations in fish yield under 30 percent C.P. treatment. In 35 percent C.P. level fish yield showed positively significant regression on ammonia-N, electrical conductivity and water temperature. In 40 percent C.P. planktonic productivity showed positively significant while ammonia-N had negatively significant regression on fish yield. However, combined contribution of these two variables towards fish yield was 68.49 percent.]]>APHA.,1971Pages: 670Pages: 670Boyd, C.E.,19812nd Edn.,Pages: 359Pages: 359Brett, J.R.,19791979pp: 599-675pp: 599-675Fogg, F.E.,1975Pages: 175Pages: 175Javed, M., M. Hassan and K. Javed,199330712Hassan, M., M. Javed and S. Hayat,1996163135New, M.B. and I. Csavas,19931993pp: 434434Pfeiffer, T.T. and R.T. Lovell,199052213217Piper, R.G., I.B. McElwain, L.E. Orme, J.P. McCraren, L.G. Flowler and J.R. Leonard,1982Soderberg, R.W.,199052155157Steel, R.G.D. and J.H. Torrie,19802nd Edn.,Pages: 633Pages: 633